title: Molecular effects of photodynamic therapy for photoaging.
abstract: OBJECTIVE
  To quantitatively examine the epidermal and dermal cellular and molecular changes that occur after photodynamic therapy of photodamaged human skin.
  
  
  METHODS
  Serial in vivo biochemical and immunohistochemical analyses after photodynamic therapy using topical 5-aminolevulinic acid (5-ALA) and pulsed-dye laser treatment.
  
  
  METHODS
  Academic referral center, Department of Dermatology, University of Michigan, Ann Arbor.
  
  
  METHODS
  A volunteer sample of 25 adults, 54 to 83 years old, with clinically apparent photodamage of the forearm skin.
  
  
  METHODS
  Three-hour application of 5-ALA followed by pulsed-dye laser therapy using non-purpura-inducing settings to focal areas of photodamaged forearms and serial biopsy specimens taken at baseline and various times after treatment.
  
  
  METHODS
  Immunohistochemical analysis was used to assess levels of markers of epidermal proliferation (Ki67), epidermal injury (cytokeratin 16), and photodamage (p53), as well as various markers of dermal collagen production (including prolyl 4-hydroxylase and heat shock protein 47, and type I procollagen). Real-time reverse transcriptase-polymerase chain reaction technology was used to quantify type I and type III collagen. Type I procollagen protein was quantified with enzyme-linked immunosorbent assay.
  
  
  RESULTS
  Epidermal proliferation was stimulated as demonstrated by increases in Ki67 (more than a 5-fold increase; P < .05) and epidermal thickness (more than a 1.4-fold increase; P < .05). Epidermal injury was produced with increased cytokeratin 16 levels demonstrated (to nearly 70-fold of baseline levels; P < .05). Upregulation of collagen production was demonstrated with increases in procollagen I messenger RNA (2.65-fold; P < .05), procollagen III messenger RNA (3.32-fold; P < .05), and procollagen I protein (2.42-fold; P < .05) levels detected. The baseline epidermal p53 level correlated with cytokeratin 16 levels at acute time points, and the latter were found to correlate with peak collagen production.
  
  
  CONCLUSIONS
  Photodynamic therapy with the specific treatment regimen employed produces statistically significant quantitative cutaneous molecular changes (eg, production of types I and III collagen) that are associated with improved appearance of the skin. Baseline epidermal p53 immunostaining levels may be predictive of dermal responses to this therapy. Comparison with historical data using pulsed-dye laser therapy alone suggests that use of the photosensitizer may enhance dermal remodeling. The quantitative in vivo molecular data presented herein are in keeping with an evolving model to potentially predict the efficacy of new techniques for the treatment of photoaging.
authors.affiliation: Department of Dermatology, University of Michigan Medical School, 1500 E Medical Center Dr, 1910 Taubman Center, Ann Arbor, MI 48109-0314, USA. jorringe@umich.edu
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Orringer
authors.forename: Craig
authors.initials: C
authors.lastname: Hammerberg
authors.forename: Ted
authors.initials: T
authors.lastname: Hamilton
authors.forename: Timothy M
authors.initials: TM
authors.lastname: Johnson
authors.forename: Sewon
authors.initials: S
authors.lastname: Kang
authors.forename: Dana L
authors.initials: DL
authors.lastname: Sachs
authors.forename: Gary
authors.initials: G
authors.lastname: Fisher
authors.forename: John J
authors.initials: JJ
authors.lastname: Voorhees
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000622:Aminolevulinic Acid / Q000627:therapeutic use*; D015415:Biomarkers / Q000378:metabolism; D024042:Collagen Type I / Q000235:genetics / Q000378:metabolism; D003131:Combined Modality Therapy; D004817:Epidermis / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D053536:Keratin-16 / Q000235:genetics / Q000378:metabolism; D019394:Ki-67 Antigen; D054025:Lasers, Dye; D028022:Low-Level Light Therapy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010778:Photochemotherapy / Q000379:methods*; D011336:Probability; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D018570:Risk Assessment; D012494:Sampling Studies; D015595:Skin Aging / Q000187:drug effects* / Q000473:pathology / Q000528:radiation effects*; D016896:Treatment Outcome; D015854:Up-Regulation
chemical_list: D015415:Biomarkers; D024042:Collagen Type I; D053536:Keratin-16; D019394:Ki-67 Antigen; D012333:RNA, Messenger; D000622:Aminolevulinic Acid